Slit lamp for ophthalmic use

ABSTRACT

A slit lamp for illuminating an eye comprises several LEDs electrically coupled to an LED driver. A user input accepts input for a length, a width and an intensity of a shaped beam of light. An LED driver selectively drives a set of LEDs of an LED array to form a shaped light beam having a desired size across a beam cross-section. In some embodiments, several optical fibers at a first end of a fiber optic manifold are optically coupled to LEDs of an LED array, and an optic is placed near a second end of a fiber optic manifold. Several ends of optical fibers of the fiber optic manifold are optically coupled to the set of selectively driven LEDs, and are arranged so as to form the shaped light beam having a desired size across the beam cross-section.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a non-provisional patent application which claims the benefitunder 35 USC 119(e) of U.S. Provisional Patent Application No.60/491,801 filed Aug. 1, 2003, the full disclosure of which isincorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

Not applicable

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK.

Not applicable

BACKGROUND OF THE INVENTION

This invention generally relates to surgical devices, systems, andmethods, and more particularly to slit lamps used to illuminate and viewan anterior segment of an eye during an ophthalmic examination.

Slit lamps are used in ophthalmic applications to view an anteriorsegment of an eye with a beam of light. The anterior segment of an eyetypically comprises a cornea, an iris, a sclera, an anterior lenscapsule, a posterior lens capsule, and/or a lens nucleus. A beam oflight is generated by the slit lamp to illuminate these tissues while auser views the illuminated area, often through a magnification opticsuch as a microscope. The beam of light can have a varying beamcross-section. For example, the beam of light will often be focused toform a narrow slit. Such a beam is desirable for examining layers of acornea of an eye. In other instances, for example when viewing a largearea of an eye, the user adjusts the beam to a wide beam cross-section.Slit lamps often pass light through a slot aperture. In many instances,the variation in the light beam is accomplished by mechanically changinga width across the slot aperture.

During Laser In-Situ Keratomileusis (LASIK) eye surgery, surgeonsevaluate quality and positioning of a LASIK incision and resulting flapof tissue with a slit lamp. The beam of light from the slit lamp is wellsuited for viewing debris under a LASIK flap and also for viewingwrinkles in a LASIK flap. Debris and flap wrinkles are appropriatelytreated and corrected upon detection with a slit lamp examination.

While ophthalmic lamps proposed to date may be generally effective forpatient examinations, further improvements would be desirable. Ingeneral, it would be desirable to provide slit lamps having decreasedsize and complexity. For example, slit lamps having fewer moving partswhile providing a variable beam of light would be desirable.

BRIEF SUMMARY OF THE INVENTION

The present invention provides improved methods and systems forilluminating an eye during an ophthalmic examination.

In one embodiment, the invention provides a lamp for selectivelyilluminating a region of an eye. An LED driver selectively drives afirst set of a plurality of LEDs so as to generate a shaped light beamilluminating the eye with a first size across a cross-section of thebeam. An input is coupled to a driver, and the driver drives a secondset of the LEDs in response to a signal from the input so as toilluminate the eye with a second beam cross-section. A secondcross-sectional size is different than a first cross-sectional size.

In some embodiments, the first cross-sectional size is related to afirst size across a first set of LEDs, and the second cross-sectionalsize is related to a second size across a second set of LEDs. The firstcross-sectional size across the first set of LEDs is different than thesecond cross-sectional size across the second set of LEDs, and the firstset of LEDs comprises LEDs from the second set of LEDs. The first set ofLEDs comprises a first number of LEDs, and the second set of LEDscomprises a second number of LEDs. The first number of LEDs is differentthan the second number of LEDs.

In specific embodiments, the first cross-sectional size is greater thanthe second cross-sectional size and the first number of LEDs is greaterthan the second number of LEDs. The first set of LEDs emits a firstamount of light energy and the second set of LEDs emits a second amountof light energy. The first amount of light energy is greater than thesecond amount of light energy. Alternatively, the first cross-sectionalsize is smaller than the second cross-sectional size, and the firstnumber of LEDs is smaller than the second number of LEDs. The first setof LEDs emits the first amount of light energy and the second set ofLEDs emits the second amount of light energy. The first amount of lightenergy is smaller than the second amount of light energy.

In a specific embodiment, the lamp is a slit lamp, and the shaped lightbeam has an elongate cross-section as the light beam illuminates theeye. The signal controls a width of the shaped light beam, a length ofthe shaped light beam, and an intensity of the shaped light beam.

In another embodiment, the invention provides a slit lamp forilluminating an eye. The slit lamp comprises an array of LEDs. An LEDdriver has a first configuration driving a first set of LEDs and asecond configuration driving a second set of LEDs. At least one opticdirects light generated by the array toward the eye. Light from theoptic comprises a beam with an elongate cross-section having a firstcross-sectional size when the LED driver is in the first configurationand a second cross-sectional size when the LED driver is in the secondconfiguration. The second cross-sectional size is different than thefirst cross-sectional size. The first cross-sectional size is oftenrelated to a first size across the first set of LEDs, and the secondcross-sectional size is often related to a second size across the secondset of LEDs. The first cross-sectional size across the first set of LEDsis different than the second cross-sectional size across the second setof LEDs.

In specific embodiments, the microscope provides a view of an anteriorsegment of the eye to a user while the light beam illuminates the eye. Amicro-lens optic is optically coupled to the LED array. The optic isselected from the group consisting of a lens, a micro-lens array and adiffractive optic. At least one LED emits white light. The slit lampcomprises at least one monolithic array of LEDs. The array of LEDs is ahybrid array of LEDs comprising LEDs from a monolithic array of LEDs andindividual LEDs. Alternatively, the array of LEDs may comprisemulticolor LEDs. The LED driver drives a portion of an LED array in thesecond configuration and the second cross-sectional size is less thanthe first cross-sectional size. A user input generates a signal. The LEDdriver drives the portion of the LED array in response to the signal.The portion of the LED array driven by the LED driver is disposed overan area. A size across the area of the portion of the LED array drivenby the LED driver corresponds to the second cross-sectional size of anelongate beam. The array of LEDs is disposed over an area, the area ofthe portion of LEDs driven by the LED driver is included within the areaof the LED array. The area of the portion of the LED array driven by theLED driver has an elongate shape.

In specific embodiments, a fiber optic manifold comprises severaloptical fibers, and has a first end and a second end. Several opticalfibers of the first end of the manifold are coupled to several LEDs ofthe LED array. The second end of the manifold emits light generated bythe LED array, and optical fibers at the second end of the manifold arearranged so as to form the beam having the elongate cross-section. Anoptic is placed at the second end of the manifold. The optic is selectedfrom the group consisting of a lens, a micro-lens array and adiffractive optic. Several ends of several optical fibers at the secondend of the manifold are optically coupled to the portion of an LED arrayand disposed over an area. A size across the area corresponds to thesecond cross-sectional size across the elongate beam.

In another aspect, the invention provides a method of selectivelyilluminating a region of an eye with a shaped beam of light. Driving afirst set of LEDs from a plurality of LEDs generates the shaped beam oflight having a first size across a cross-section of the shaped beam. Auser input generates a signal. Driving a second set of the plurality ofLEDs in response to the signal from the user input generates the shapedlight beam having a second size across a cross-section of the shapedbeam. The second cross-sectional size is different from the firstcross-sectional size.

In many embodiments, the first set of LEDs overlaps with the second setof LEDs. The signal effects a change in a number of driven LEDs. Thesignal from the user input can result in a reduction from the firstcross-sectional size to the second cross-sectional size. The first setof LEDs can emit a first amount of light energy and the second set ofLEDs can emit a second amount of light energy so that the signalprovides a reduction from the first amount of light energy to the secondamount of light energy. Alternatively, the first cross-sectional sizecan be smaller than the second cross-sectional size and the first numberof LEDs can be smaller than the second number of LEDs. The first set ofLEDs can emit a first amount of light energy and the second set of LEDscan emit a second amount of light energy so that the signal provides anincrease from the first amount of light energy to the second amount oflight energy.

In specific embodiments, a plurality of LEDs comprises several sets ofLEDs. The several sets of LEDs have a different number of LEDs, each setof LEDs being selectably energized by the driver so as to providevarying beam characteristics. The second set of LEDs can comprise anumber of LEDs that is less than a total number of LEDs. The pluralityof LEDs comprises an array of LEDs. The shaped light beam has anelongate cross-section near the eye. The second cross-sectional size maycomprise a width across the beam cross-section, and the secondcross-sectional size may comprise a length across the beamcross-section. The shaped beam can be transmitted through a bundle ofoptical fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a slit lamp having a shaped beam of lightilluminating an eye in which a width across a shaped beam is determinedby a number of LEDs used to illuminate an eye in accordance with anembodiment of the invention.

FIG. 1A. illustrates different sizes across a cross-section of a shapedbeam in accordance with an embodiment of the invention.

FIG. 2 illustrates a slit lamp using a fiber optic manifold to couplelight energy from an LED array to a micro-lens array in accordance withan embodiment of the invention.

FIG. 2A illustrates a second end of a optical fiber manifold comprisingan array of several ends of optical fibers disposed over an area inaccordance with an embodiment of the invention

FIG. 2B illustrates a beam of light having a rectangular cross-sectionin accordance with an embodiment of the invention.

FIG. 3 illustrates a slit lamp having an elongate cylindrical shape thatcan be held in a hand of a user and having external controls adjustableby a user in accordance with an embodiment of the invention.

FIG. 4 illustrates an LED driver circuit for driving several LEDs inresponse to a user input at a control in accordance with an embodimentof the invention.

FIG. 4A illustrates an LED driver comprising a processor and displaydriver in accordance with an embodiment of the invention.

FIG. 5 illustrates a lens imaging light emitted by an LED array inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to systems and methods ofilluminating an eye with light, and more specifically to systems andmethods of illuminating an anterior segment of an eye with slit lamp.

As illustrated in FIG. 1, an eye 2 having a cornea 4 and an iris 6 isilluminated with a slit lamp 1 having a shaped beam of light 8 having across-section 9 with a size 10 across a cross-section 9 in accordancewith an embodiment of the invention. An LED array 12 is positioned neara micro-lens array 16. LED array 12 comprises a plurality of individualLEDs such as LEDs 13, 14 and 15. Micro-lens array 16 is positioned afocal length from individual LEDs to collimate light emitted from LEDsas the shaped light beam 8, which travels toward the eye 2. A portion ofLED array 12 comprising LEDs 13 and 14 emits light. The size 10 acrossthe cross-section 9 of the beam 8 is determined by a number of LEDsemitting light. An eye 24 of an operator is able to view the eye 2through a microscope 22.

An LED driver 18 selectively drives LEDs 12, 13 and 14 of LED array 12.A user input device 30 is operationally coupled to LED driver 18 with anelectrical connection 19. The user input device 30 includes a firstcontrol 32 that adjusts the size 10 across the cross-section 9 of theshaped light beam 8. The first user control 32 sends an electricalsignal to the LED driver 18. The LED driver 18 selectively drives LEDsof the LED array 12 in response to a signal from the first user control32. A second control 34 of the user input 30 adjusts an intensity of thelight beam 8.

As illustrated in FIG. 1A, the eye 2 having the cornea 4 and the iris 6is illuminated with slit lamp 1 in accordance with the embodiment of theinvention as in FIG. 1. The LED driver 18 selectively drives anycombination of LEDs 13, 14 and 15 in response to a signal from control30. In a first state the LED driver 18 drives a first set of LEDscomprising LEDs 13 and 14 so as to form the shaped light beam 8 havingthe size 10 across cross-section 9. A second state of LED driver 18drives a second LED set comprising LED 13 so as to form shaped lightbeam 8 having a size 10A across cross-section 9. A third state of LEDdriver 18 drives a third set of LEDs comprising LEDs 13, 14 and 15 so asto form shaped light beam 8 having a size 10B across cross-section 9.

Referring to FIG. 2, an exemplary embodiment of a slit lamp using a twodimensional array of LEDs and having an elongate beam adjustable alongtwo sizes of a beam cross-section is illustrated in accordance with anembodiment of the invention. An array of LEDs 50 comprises a pluralityof LEDs, for example LEDs 52, 54, 56 and 58. LEDs of the array 50 arearranged in horizontal rows and vertical columns. For example LEDs 52and 58 are disposed in the same column as LEDs 54 and 56, and LEDs 52and 54 are disposed in the same row as LEDs 56 and 58. An individual LEDof an array is expressed in matrix notation as LED (Row, Column). Forexample, LEDs 52, 54, 56 and 58 are expressed as LED (1,1), LED (1,3),LED (15, 3) and LED (15,1) respectively. In an alternate embodiment anLED array comprises a linear array of LEDs coupled to optical fibers. Anadditional embodiment comprises an array of LEDs having variable spacingbetween LEDs. An LED preferably emits white light. Suitable LEDs includewhite light LEDs having a model number LW A67C, commercially availablefrom OSRAM Opto Semiconductors, San Jose, Calif. and Regensburg,Germany. Any LED can be used in LED array 50. For example, in someembodiments an LED array comprises a monolithic LED array commerciallyavailable as a custom order from PRP OPTOELECTRONICS ofNorthamptonshire, England. In some embodiments, any color of light ismade by combining light from several LEDs in which each LED emits lighthaving any one of the colors of red, blue and green. For example, whitelight is made by combining light from several LEDs in which each of theLEDs emits light having any one of the colors of red, blue and green.

An optical fiber manifold 60 has a first end 66 and a second end 68.Individual LEDs of the LED array 50 are optically coupled to individualoptical fibers of the first end 66 of the fiber optic manifold 60. Anynumber of known techniques and structures can be used to opticallycouple an LED with an optical fiber. For example, in a preferredembodiment, light from an LED is coupled to an optical fiber usingdirect proximity coupling, also referred to as butt coupling. Inalternate embodiments an optic is used to couple light into an opticalfiber. Any optic selected from the group consisting of a single lens, alens array and a diffractive optic can be used to couple light into anoptical fiber. The optic is placed at a suitable distance from the LEDso that light is optimally coupled into the optical fiber. For example,a convergence angle of an emitted cone of light and a numerical apertureof the optical fiber are matched. In a preferred embodiment, anindividual optical fiber 61 of the fiber optic manifold 60 has a firstend 62 and a second end 72A. Any optical fiber can be used in the fiberoptic manifold 60, for example a multimode fiber model F-MBB availablefrom NEWPORT CORPORATION, Irvine, Calif., and an InfiniCor® SXI opticalfiber available from CORNING INC., Corning, N.Y.

In some embodiments, the fiber optic manifold 60 comprises an imagepreserving bundle of optical fibers, also referred to as a coherentbundle, such as a fiber optic bundle model number IG 163A available fromSchott Fiber Optics, Southbridge Mass. A suitable fiber optic bundle iscommercially available as a custom order from PAGE AUTOMATEDTELECOMMUNICATION, INC., Mountain View, Calif. The first end 62 ofoptical fiber 61 may be optically coupled to any LED, for example LED52. The second end 68 of the fiber optic manifold 60 is opticallycoupled to a micro-lens array 70.

The micro-lens array 70 comprises 5 columns and 20 rows having a totalnumber of 100 micro-lenses. The micro-lens array 70 comprises severalindividual micro-lenses, for example micro-lenses 72, 74, 76 and 78. Amicro-lens array having a part number 0500-45-S is commerciallyavailable from ADAPTIVE OPTICS, INC. of Cambridge, Mass. Similarmicro-lens arrays can be used. Preferably, each micro-lens is opticallycoupled to an end of an individual optical fiber so as to avoid crosstalk. For example, the micro-lens 72 is optically coupled to the secondend 72A of the optical fiber 61. The lenses of the micro-lens array 70are preferably positioned a focal length away from an end of an opticalfiber. Each LED is predominantly coupled to a micro-lens with a singleoptical fiber. For example LEDs 52, 54, 56 and 58 are optically coupledto the micro-lenses 72, 74, 76 and 78 respectively. Any number of knowntechniques and structures as described above can be used to opticallycouple optical fibers with optics at the second end 68 of the fiberoptic manifold 60. For example, any optic selected from the groupconsisting of a single lens, a lens array, and a diffractive optic canbe used. The fiber is placed at a position close to a focal length ofthe selected optic. In some embodiments, a mechanical aperture is placedat the second end 68 of the fiber optic manifold 60 to shape an emittedbeam of light. Each micro-lens emits a beam of collimated light towardeye 2. In an alternate embodiment, a micro-lens array comprises adiffractive optical element having a repeating pattern of diffractiveoptical elements designed to minimize spherical aberration.

User input device 30 as described above comprises a user input control82. The control 82 accepts input from a user. Any input device can beused as user input device 30 including keyboards, joysticks, trackballs,mice keypads, push button pads, and any input device of the VISX STARS4™, which is commercially available from VISX, INCORPORATED of SantaClara, Calif. A first control 84 adjusts a length of shaped light beam 8as described above. A second control 86 adjusts a width of shaped lightbeam 8 as described above, and a third control 88 adjusts an intensityof shaped light beam 8 as described above. In an alternate embodiment,an additional input adjusts a color of a light beam. An LED driver 90 isoperationally coupled to the user input control 82 by an electricalconnection 80 comprising a plurality of wires, for example wires 80A,80B, and 80C. The wires 80A, 80B and 80C are interwoven among severaloptical fibers of manifold 60 to form a single cable 65. In anembodiment, wires 80A, 80B and 80C comprise a cable separate from fiberoptic manifold 60. The LED driver 90 receives signals from the userinput control 82 transmitted over the electrical connection 80comprising the wires 80A, 80B and 80C. The LED driver 90 selects a setof LEDs from the array 50 in response to signals transmitted from theuser input device 30.

In an embodiment, the LED driver 90 controls each individual LEDindependently. By providing individual control of each LED, the widthand the length of the light beam can be changed in very smallincrements. A minimum size of such an incremental change beam size isrelated to spacing between the LEDs and the optical fibers. Also, suchindividual control of LEDs permits any cross-sectional shape of lightbeam to made. For example, a set of LEDs can be selected to form a beamwith a cross-section having crescent shape. Selected LEDs are driven andemit light. The intensity of light emitted from a set of selected LEDsis also adjusted by LED driver 90 in response to signals from the userinput control 82. The LED driver 90 adjusts an electrical drive currentpassing through a selected LED. Hence, a user is able to adjust theintensity of light emitted from the set of selected LEDs. The LED driver90 is electrically coupled to the LED array 50 with electrical wires 92.An electrical power supply cord 94 passes electrical current to the LEDdriver 90 and supplies the LED driver 90 with electrical energy. An LEDmodule 98 comprises the LED array 50 and the LED driver 90.

As illustrated in FIG. 2A, the second end 68 of the optical fibermanifold 60 comprises an array 70A of several ends of optical fibersdisposed over an area in accordance with an embodiment of the invention.For example, the second end 72A of the optical fiber 61 and ends 74A,76A, and 78A of additional optical fibers are disposed over a generallyrectangular area of the second end 68 of the optical fiber manifold 60.The array 70A of optical fibers ends having 5 columns and 20 rowscomprises a total number of 100 optical fiber ends. The optical fiberends 72A, 74A, 76A and 78A are optically coupled to the micro-lenses 72,74, 76 and 78A respectively.

To form a generally rectangular shaped beam of light, the LED driverselectively activates a set of LEDs comprising each LED within arectangular area, for example an area bounded by the LEDs 52,54, 56 and58. A first set of LEDs are optically coupled to each optical fiber endwithin a generally rectangular area bounded by the optical fiber ends72A, 74A, 76A and 78A, and each diffractive optic within a generallyrectangular area bounded by the micro-lenses 72, 74, 76 and 78. Aportion of an array 70 optical fiber ends comprising 3 columns and 16rows having a total number of 48 optical fibers are optically coupled toa portion of the array 50 comprising 48 LEDs disposed over a rectangulararea of the LED array 50. The LED array 50 comprises 5 columns and 20rows having a total number of 100 LEDs. A rectangular area of the LEDarray 50 comprising 3 columns and 16 rows is bounded on four corners bythe LEDs 52, 54, 56 and 58. The LED driver 90 selects and drives LEDswithin the rectangular region bounded by LEDs 52, 54, 56 and 58 to emitlight from the rectangular region of the LED array 50. Light emittedfrom the rectangular region comprising a portion of LED array 50 isemitted from a rectangular region comprising a portion of fiber opticarray 70A bounded by the optical fiber ends 72A, 74A, 76A and 78A asdescribed above. Light from the fiber optic array 70 forms a beam oflight having a rectangular cross-section.

Referring to FIG. 2B, a beam of light 8A having a rectangularcross-section 9A is illustrated in accordance with an embodiment of theinvention. Sizes across beam cross-section 9A include a width 11A acrosscross-section 9A and a length 11B across the cross-section 9A. Any sizeacross a cross-section of beam 8A is determined by LEDs selectivelydriven by the LED driver. The width 11A across the cross-section of beam8A is determined by a number of columns of LEDs driven by the LEDdriver. The length 11B across the cross-section 9A is determined by anumber of rows driven by the LED driver. For example, a first set ofLEDs comprising a portion of the LED array 50 is bounded by LED (1,1),LED (1,3), LED (15, 3) and LED (15,1) respectively as described above. Afirst configuration of the LED driver driving 45 LEDs comprises thefirst set of LEDs so as to produce a beam having a first width 11Aacross the cross-section 9A and a first length 11B across thecross-section 9A. A second set of LEDs comprising a portion of the LEDarray 50 is bounded by LED (1,1), LED (1,2), LED (15,2) and LED (15,1).A second configuration of the LED driver driving 30 LEDs comprises thesecond set of LEDs so as to produce a beam having a second width 11Aacross the cross-section 9A and the first length 11B acrosscross-section 9A. The second width 11A is less than the first width 11Aacross cross-section 9A. A third set of LEDs comprising a portion of LEDarray 50 is bounded by LED (1,1), LED (1,2), LED (10,2) and LED (10,1).A third configuration of the LED diver driving 20 LEDs comprises thethird set of LEDs so as to produce a beam having the second width 11Aacross cross-section 9A and the second length 11B across thecross-section 9A. The second length 11B is less than the first length11B across the cross-section 9A. Any length and width can be selectedwith any set of LEDs.

Any LEDs of the LED array comprise a set of LEDs. For example, thefollowing LEDs comprise a set of LEDs: LED(L,1), LED (2,2), LED (3,3),LED (4,4), LED (5,5), and LED (10, 4). Several sets of LEDs exist, and anumber of usable sets of LEDs exceeds a number of LEDs in the array. Anamount of light energy emitted by an LED is approximately the same foreach LED driven by the LED driver having similar electrical parameters,e.g. current. A subsequent amount of light energy emitted by a set ofLEDs is proportional to a total number of LEDs comprised within the set.Therefore, an amount of light energy emitted by a first set of 45 LEDsis greater than an amount of light energy emitted by a second set 30LEDs, and the amount of light energy emitted by the second set of 30LEDs is greater than an amount of light energy emitted by a third set of20 LEDs.

Referring to FIG. 3, a slit lamp having an elongate cylindrical shapethat can be held in a hand of a user and having external controlsadjustable by the user is illustrated in accordance with an embodimentof the invention. A single cable 65 comprises a fiber optic manifold andcontrol wires as described above. The LED module 98 comprising the LEDarray 50 is optically coupled to the cable 65 as described above. Thepower supply cord 94 supplies electrical energy to the LED module 98 asdescribed above. The user input control 82 transmits signals to the LEDmodule 98 as described above. The micro-lens array 70 is opticallycoupled to the cable 65 as described above. Light emitted from themicro-lens array 70 forms the shaped beam as the light beam travelstoward the eye as described above.

Referring to FIG. 4, an LED driver 100 having a circuit for drivingseveral LEDs in response to a user input at a control is illustrated inaccordance with an embodiment of the invention. Signals from the userinput control communicated along control wires 102, 104 and 106 controlthe length, the width and the intensity of the shaped light beam. A gatearray 108 comprises a Stratix™ EP1S10 field programmable gate arrayhaving 426 user input/output pins, and is available from ALTERACORPORATION located in San Jose, Calif. A digital to analog converter112 is electrically coupled to the gate array 108 with electrical wires110 attached to output pins 109A, 109B, 109C, 109D and 109E of the gatearray 108. The digital to analog converter 112 is electrically coupledto an amplifier 116 with a wire 114. The digital to analog converter 112outputs a voltage to the amplifier 116. The amplifier 116 iselectrically connected in parallel to transistors 118, 120 and 122 withwires 115, 117 and 119. The amplifier 116 applies a voltage to thetransistors 118, 120 and 122. Gate array outputs 128, 130 and 132 areelectrically coupled to gates of the transistors 118, 120 and 122 withwires 129, 131 and 133, respectively. LEDs 148, 150 and 152 areelectrically coupled to the transistors 118, 120 and 122 respectivelywith the wires 149, 151 and 153. The gate array outputs 128, 130 and 132selectively turn on the LEDs 148, 150 and 152 respectively in responseto the user inputs 102 and 104. An intensity of light output by the LEDs148, 150 and 152 is determined by a voltage applied to the transistors118, 120 and 122. The voltage applied to the transistors 118, 120 and122 is determined by signals from the output pins 109A-109E in responseto the user input 106. The gate array 108 is programmed to selectivelyactivate LEDs of the LED array to control the length and the widthacross the beam of light illuminating the eye as described above. Whilethree LEDs are shown in FIG. 4, several hundred LEDs can be driven byadditional pins of the gate array. For example, each individual LED ofLED array 50 comprising 100 LEDs as described above is readily driven bythe LED driver scheme illustrated in FIG. 4. Any gate array can be usedto drive any number of LEDs. For example, a Stratix™ EP1S80, availablefrom ALTERA CORPORATION, has 1,203 input output pins, and can drive overone thousand LEDs.

Referring to FIG. 4A, an LED driver 158 comprises a processor 162 and adisplay driver 166 in accordance with an embodiment of the invention. Acable 160 electrically connects the processor 162 to the input device asdescribed above and passes electrical signals between the processor 162and the input device. A processor comprises elements of a pc workstationincluding a central processing unit (CPU) such as an Intel Pentium®processor available from INTEL CORPORATION of Santa Clara, Calif. Theprocessor 162 comprises a tangible medium 163. The tangible medium 163comprises any data storage medium such as a floppy disk drive, CD ROMdrive and erasable programmable read only memory (EPROM). A bus 164electrically connects the processor 162 with a display driver 166.Suitable display drivers are a MAX6953 available from MAXIM INTEGRATEDPRODUCTS, INC., Sunnyvale Calif., and LM3354, LM3355 and FPD33684display drivers available from NATIONAL SEMICONDUCTOR of Santa Clara,Calif. The display driver 166 is electrically connected to an LED array170 using wires 168. A signal from an operator input is transmitted overthe cable 160 and the processor 162 selects any set of LEDs and anyintensity of driven LEDs in response. A computer program is stored onthe tangible medium 163 and comprises instructions for selecting LEDsand intensities of LEDs in response to signals from an operator inputdevice. A signal is transmitted from a computer 162 to a display driver166 over a bus 164. The LED driver 166 drives LEDs of LED array 170 inresponse to signals from an operator input so as to control a shape andan intensity of a light beam as described above.

Referring to FIG. 5, a lens 204 imaging light emitted by an LED array200 is illustrated in accordance with an embodiment of the invention. Aset 202 of LEDs comprising a portion of the LED array 200 is disposedover an area and selected by the LED driver to emit light as describedabove. The Lens 204 images light emitted from LED array 200 to form ashaped light beam 8B comprising an image of the set 202 of driven LEDsnear the eye 2. The light beam 8 b has a rectangular cross-section 9Bnear eye 2. In an alternate embodiment, the lens 204 images lightemitted by optical fibers disposed over an area as described above so asto from the shaped light beam having a rectangular cross-section.

While exemplary embodiments of the present invention have been describedin some detail, by way of example and for clarity of understanding, avariety of changes, modifications, and adaptations will be obvious tothose of skill in the art. For example, embodiments of above describedslit lamp may be integrated with any operating microscope and anyrefractive laser surgery system, for example a Star S4™ Excimer LaserSystem, available from VISX, INCORPORATED of Santa Clara, Calif.Further, any light source including lasers and incandescent lights canbe selected and driven with electrical power to emit light and form ashaped beam. Also, while reference has been had to rectangular beams oflight, systems and methods of the present invention can be used to makea light beam having a cross-section with any shape. Hence, the scope ofthe present invention is limited solely by the appended claims.

1. A lamp for selectively illuminating a region of an eye comprising: aplurality of LEDs; an LED driver selectively driving a first set of theplurality of LEDs to generate a shaped light beam illuminating the eyewith a first size across a cross-section of the beam; and an inputcoupled to the driver, the LED driver driving a second set of the LEDsin response to a signal from the input, the second set being differentfrom the first set so as to illuminate the eye with the shaped lightbeam having a second size across the cross-section of the beam, thesecond size being different than the first size.
 2. The lamp of claim 1wherein the first cross-sectional size is related to a first size acrossthe first set of LEDs, and the second cross-sectional size is related toa second size across the second set of LEDs, the first cross-sectionalsize across the first set of LEDs being different than the secondcross-sectional size across the second set of LEDs.
 3. The lamp of claim1 wherein the first set of LEDs comprises LEDs from the second set ofLEDs.
 4. The lamp of claim 1 wherein the first set of LEDs comprises afirst number of LEDs, and the second set of LEDs comprises a secondnumber of LEDs, the first number of LEDs different than the secondnumber of LEDs.
 5. The lamp of claim 4 wherein the first cross-sectionalsize is greater than the second cross-sectional size and the firstnumber of LEDs is greater than the second number of LEDs.
 6. The lamp ofclaim 5 wherein the first set of LEDs emits a first amount of lightenergy and the second set of LEDs emits a second amount of light energy,the first amount of light energy greater than the second amount of lightenergy.
 7. The lamp of claim 4 wherein the first cross-sectional size issmaller than the second cross-sectional size and the first number ofLEDs is smaller than the second number of LEDs.
 8. The lamp of claim 7wherein the first set of LEDs emits a first amount of light energy andthe second set of LEDs emits a second amount of light energy, the firstamount of light energy smaller than the second amount of light energy.9. The lamp of claim 1 wherein the lamp is a slit lamp and the shapedlight beam has an elongate cross-section as the light beam illuminatesthe eye.
 10. The lamp of claim 1, wherein the signal controls a width ofthe shaped light beam.
 11. The lamp of claim 1 wherein the signalcontrols a length of the shaped light beam.
 12. The lamp of claim 1wherein the signal controls an intensity of the shaped light beam.
 13. Aslit lamp for illuminating an eye comprising: an array of LEDs; a LEDdriver having a first configuration driving a first set of LEDs and asecond configuration driving a second set of LEDs; and at least oneoptic directing light generated by the array toward the eye, the lightfrom the optic comprising a beam with an elongate cross-section having afirst size across a cross-section of the beam when the LED driver is inthe first configuration and a second size across a cross-section of thebeam while the LED driver is in the second configuration, the first setof LEDs being different from the second set of LEDs so that the secondcross-sectional size is different than the first cross-sectional size.14. The slit lamp of claim 13 wherein the first cross-sectional size isrelated to a first size across the first set of LEDs, and the secondcross-sectional size is related to a second size across the second setof LEDs, the first cross-sectional size across the first set of LEDsbeing different than the second cross-sectional size across the secondset of LEDs.
 15. The slit lamp of claim 13 further comprising amicroscope providing a view of an anterior segment of the eye to a userwhile the light beam illuminates the eye.
 16. The slit lamp of claim 13further comprising an optic coupled to the LED array.
 17. The slit lampof claim 16 wherein the optic is selected from the group consisting of amicro-lens array, a diffractive optic and a lens.
 18. The slit lamp ofclaim 13 further comprising at least one LED emitting white light. 19.The slit lamp of claim 13 further comprising at least one monolithicarray of LEDs.
 20. The slit lamp of claim 13 wherein the array of LEDsis a hybrid array of LEDs comprising LEDs from a monolithic array ofLEDs and individual LEDs.
 21. The slit lamp of claim 13 wherein thearray of LEDs comprises multicolor LEDs.
 22. The slit lamp of claim 13wherein the LED driver drives a portion of the LED array in the secondconfiguration and the second cross-sectional size is less than the firstcross-sectional size.
 23. The slit lamp of claim 22 further comprising auser input generating a signal, the LED driver driving the portion ofthe LED array in response to the signal.
 24. The slit lamp of claim 22wherein, the portion of the LED array driven by the LED driver isdisposed over an area, a size across the area of the portion of the LEDarray driven by the LED driver corresponding to the secondcross-sectional size of the elongate beam.
 25. The slit lamp of claim 24wherein the array of LEDs is disposed over an area, the area of theportion of LEDs driven by the LED driver being included within the areaof the LED array.
 26. The slit lamp of claim 25 wherein the area of theportion of the LED array driven by the LED driver has an elongate shape.27. The slit lamp of claim 22 further comprising a fiber optic manifoldhaving several optical fibers, the manifold having a first end and asecond end, several optical fibers of the first end of the manifoldbeing coupled to several LEDs of the LED array, the second end of themanifold emiffing light generated by the LED array, and the opticalfibers at the second end of the manifold being arranged so as to formthe beam having the elongate cross-section.
 28. The slit lamp of claim27 wherein several ends of the several optical fibers at the second endof the manifold are optically coupled to the portion of the LED arrayand disposed over an area, a size across the area corresponding to thesecond cross-sectional size across the elongate beam.
 29. The slit lampof claim 22 wherein an optic is placed at the second end of themanifold.
 30. The slit lamp of claim 29 wherein the optic is selectedfrom the group consisting of a lens, a microlens array and a diffractiveoptic.